Phased array theory and technology have been in existence for more than 30 years. Phased array antennae have been used most extensively in the past in military systems, such as airborne and ground-based fire control radar systems. They do have several common problems relating to high cost, including the relatively high cost of: a) phase shifter technology; b) phase shifter beam steering controller networks; and c) the high number of RF and control interconnects required for phased array antennae of even moderate size. As an example, a two-dimensional array of one thousand radiating elements can often require up to one thousand phased shifters, each with commensurate RF interconnect, digital control, and a sophisticated system level beam steering computer. While standard techniques, such as sub-arraying and row/column phase shifter steering, help reduce the interconnect problem with reduced performance, cost is still a major issue. Even state-of-the-art monolithic microwave integrated circuit (MMIC) based active phased arrays suffer from excessive cost.
Another prior art approach is described in U.S. Pat. No. 5,583,524. While this design has considerable benefits, it does have some drawbacks. It is not the most ideal antenna for all applications.
Consequently, there is a need for improvements in affordable phased array antenna systems.